Vasospasm due to massive subarachnoid haemorrhage--a rat model.

Although the pathophysiology of chronic cerebral vasospasm following subarachnoid haemorrhage (SAH) is still unclear, it is certain that the amount of subarachnoid blood is predictive of the severity of cerebral vasospasm. Accordingly, massive subarachnoid haemorrhage (greater than 0.5 ml) was induced in adult rats via direct injection into the cisterna magna. Compared to other previously published models of experimental SAH in rats a much larger amount of blood was injected. The basilar artery was exposed 72 hours post subarachnoid haemorrhage and photographed under controlled conditions. The diameter of the artery was assessed by an image analyzer. A 50% reduction in diameter was found in 25 rats subjected to SAH as compared to 9 control rats and 4 rats with intracisternal saline injection. We conclude that when massive subarachnoid haemorrhage is induced, and direct measurements of the basilar artery are made, the rat can be used as a reliable model for investigation of SAH induced arterial vasospasm.